This invention relates to a method for manufacturing a decorative sheet having a pattern on the surface thereof.
Conventionally, plates made of stainless steel etc. have been used as base plates for decorative sheets. Etching is one of the methods for making recessed and projected patterns on the surface of regular carbon steel plates. In an etching process, grooves whose depths are about 0.1 to 0.2 mm are formed on the surface of the steel plate by chemical corrosion, thereby forming a decorative plate having a predetermined pattern.
However, such conventional decorative sheets have a problem in that the stainless steel is expensive.
Decorative sheets are sometimes used in hoistway doors, car doors etc. of an elevator. Such decorative sheets such as the decorative sheet disclosed in Japanese Laid-Open Utility Model Publication No. 59-54478 are made by applying a coating material onto the bottom of an etched groove of a sheet. FIGS. 1 and 2 show such a decorative sheet. In these figures, a decorative sheet comprises a metallic plate 101 forming a hoistway door, and grooves 102 are formed on the surface of the metallic plate 101 by etching. The bottom of each groove 102 is coated by a transparent or opaque coating material 103. Grooves 104 are also formed on the surface of the sheet 101 by etching and are narrower than the widths of the grooves 102. The bottom of each groove 104 is coated by a similar coating material 105. Thus the decorative sheet is made by forming grooves 102, 104 and coating materials 103, 105.
However, such a conventional method for manufacturing a decorative sheet has the disadvantage that although various color tones can be expressed by paint, it is difficult to obtain a solid appearance only by the paint.
Furthermore, the method using etching has certain disadvantages in that it is necessary to prepare a chemical liquid for etching and it often takes a long time to manufacture a decorative sheet since materials are collected within a certain period and thereafter etched together with each other in the same liquid and such a period for collecting materials is often long, and that it also tends to generate pollution during the treatment of the sump solution, the complete treatment of which is also very expensive.
Furthermore, it is necessary to use an expensive decorative base plate made of aluminum and stainless steel for example, and the appearance of high quality as obtained from the combination of a plurality of metals cannot be obtained.
In another method for manufacturing a decorative sheet, an embossing process has been used in which a metallic plate is pressed by a roller provided with a projected pattern to form a pattern on the surface of the plate.
However, the embossing method has other disadvantages in that the depth of the pattern is shallow and it is not suitable for especially a thick metallic plate, and the edge portions of the pattern are rounded and sharp edges are difficult to form.
To overcome the above disadvantages, an object of the present invention is to provide a method for manufacturing a decorative sheet in which the sheet has a solid appearance of high quality and the edge portions of a pattern on the sheet can be formed to be clear-cut and distinct.
Another object of the present invention is to provide a method for manufacturing a decorative sheet in which the decorative sheet can be cheaply manufactured and the portions of the sheet formed by the unevenness of the processing thereof do not stand out.
Another object of the present invention is to provide a method for manufacturing a decorative sheet in which a layer formed on the sheet has a volume corresponding to at least the volume of the pattern on the sheet.
Another object of the present invention is to provide a method for manufacturing a decorative sheet in which the decorative sheet has an intricate pattern thereon.
With the above objects in view, the present invention, according to the first embodiment thereof, resides in a method for manufacturing a decorative sheet from a metallic sheet comprising the steps of flame-spraying a coating material onto the surface of the metallic sheet to form a flame-sprayed layer thereon, and roughening the surface of the flame-sprayed layer.
The present invention, according to the second embodiment thereof, resides in a method for manufacturing a decorative sheet from a metallic sheet comprising the steps of etching the surface of the metallic sheet to form an etched pattern therein, and flame-spraying a material different from the material of the metallic sheet only on the etched pattern of the metallic sheet through a mask.
The present invention, according to the third embodiment thereof, resides in a method for manufacturing a decorative sheet from a metallic sheet comprising the steps of selectively flame-spraying a first coating material onto the surface of the metallic sheet through a first mask to form a pattern of a first coating layer, and flame-spraying a second coating material onto at least a portion of the uncoated surface of the metallic sheet which is not coated by the first coating layer through a second mask to form a second pattern of a second coating layer.